Melt butter in a 3-qt. heavy saucepan over medium heat; add sugar and lemon juice, and cook, stirring constantly with a long-handled wooden spoon, 8 to 10 minutes or until mixture turns light golden brown. Gradually add cream, and cook, stirring constantly, 1 to 2 minutes or until smooth. (Mixture will bubble and spatter when adding cream.) Remove from heat, and cool 30 minutes.